Telephone line seizure circuit

Telephone line switch using an optocooupler

Telephone on-hold device

Telephone plug system

Telephone power supply

Telephone privacy device

Telephone receiver circuit with dynamic sidetone signal...

Telephone receiver transmitter device

Telephone set

Telephone set

Telephone set comprising a line voltage stabilizer having a DC s

Telephone set having a volatile memory

Telephone set in which an echo signal is effectively cancelled i

Telephone set line status display

Telephone set usable as an acoustic coupler

Telephone set which can be adjusted in response to ambient noise

Telephone set with background noise suppression function

Telephone set with circuit for suppression of howling and echo

Telephone subscriber system incorporating a drive interface for

Telephone system allowing hold releasing request from central of